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Fix race condition of memory mappings during start-up. (#126)

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* Fix a system_malloc() race during start-up.  This should address issues #100 and #13
This commit is contained in:
Don Porter
2018-02-06 08:48:53 -08:00
committed by Chia-Che Tsai
parent 8205b08aa5
commit 181f9ea988
2 changed files with 18 additions and 6 deletions
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LibOS/shim/src/bookkeep/shim_vma.c
+2 -2
View File
@@ -891,7 +891,7 @@ static struct shim_vma * __lookup_supervma (const void * addr, uint64_t length,
struct shim_vma ** pprev)
{
struct shim_vma * tmp, * prev = NULL;
listp_for_each_entry(tmp, &vma_list, list) {
if (test_vma_contain(tmp, addr, length)) {
if (pprev)
@@ -903,7 +903,7 @@ static struct shim_vma * __lookup_supervma (const void * addr, uint64_t length,
if (!(!prev || prev->addr + prev->length <= tmp->addr)) {
struct shim_vma * tmp2;
warn("Failure\n");
uint64_t last_addr = 0;
void * last_addr = NULL;
listp_for_each_entry(tmp2, &vma_list, list) {
warn ("Entry: %llx..%llx (%llx)\n", tmp2->addr, tmp2->addr + tmp2->length, tmp2->length);
// Don't do an infinite dump if the list gets corrupted
LibOS/shim/src/shim_malloc.c
+16 -4
View File
@@ -145,18 +145,30 @@ static struct shim_heap * __alloc_enough_heap (size_t size)
return heap;
}
/* Returns NULL on failure */
void * __system_malloc (size_t size)
{
size_t alloc_size = ALIGN_UP(size);
void *addr;
void *addr, *addr_new;
lock(shim_heap_lock);
if (vmas_initialized) {
addr = (void *) DkVirtualMemoryAlloc(NULL, alloc_size, 0,
PAL_PROT_WRITE|PAL_PROT_READ);
/* If vmas are initialized, we need to request a free address range
* using get_unmapped_vma(). The current mmap code uses this function
* to synchronize all address allocation, via a "publication"
* pattern. It is not safe to just call DkVirtualMemoryAlloc directly
* without reserving the vma region first.
*/
int flags = MAP_PRIVATE|MAP_ANONYMOUS|VMA_INTERNAL;
addr = get_unmapped_vma(alloc_size, flags);
if (!addr) return NULL;
addr_new = (void *) DkVirtualMemoryAlloc(addr, alloc_size, 0,
PAL_PROT_WRITE|PAL_PROT_READ);
if (!addr_new) return NULL;
assert (addr == addr_new);
bkeep_mmap(addr, alloc_size, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS|VMA_INTERNAL, NULL, 0, NULL);
flags, NULL, 0, NULL);
} else {
struct shim_heap * heap = __alloc_enough_heap(alloc_size);